Overview

Relevant source files

Cargo.toml

README.md

src/lib.rs

The arm_pl011 crate provides type-safe register definitions and basic operations for the ARM PL011 UART controller. This library serves as a hardware abstraction layer for embedded systems and operating system kernels that need to interface with PL011 UART hardware found in ARM-based systems.

The crate is designed for no_std environments and integrates with the ArceOS operating system ecosystem, though it can be used independently in any Rust embedded project requiring PL011 UART support. For detailed hardware specifications and register layouts, see Hardware Reference. For specific implementation details, see Core Implementation.

System Context

The following diagram illustrates how arm_pl011 fits within the broader embedded systems software stack:

System Integration Context

flowchart TD
subgraph subGraph2["Hardware Layer"]
    MMIO["Memory-mapped I/O"]
    PL011_HW["PL011 UART Controller"]
    SerialPort["Physical Serial Port"]
end
subgraph subGraph1["Hardware Abstraction"]
    arm_pl011["arm_pl011 crate"]
    Pl011Uart["Pl011Uart struct"]
    tock_registers["tock-registers"]
end
subgraph subGraph0["Application Layer"]
    UserApp["User Applications"]
    Kernel["ArceOS Kernel"]
    Bootloader["Bootloader"]
end

Bootloader --> arm_pl011
Kernel --> arm_pl011
MMIO --> PL011_HW
PL011_HW --> SerialPort
Pl011Uart --> tock_registers
UserApp --> arm_pl011
arm_pl011 --> Pl011Uart
tock_registers --> MMIO

Sources: Cargo.toml(L8 - L12) README.md(L7 - L9)

Crate Structure and Code Entities

The crate follows a minimal, focused design with clear separation between public API and internal implementation:

Code Organization and Key Entities

flowchart TD
subgraph subGraph3["Build Targets"]
    linux_gnu["x86_64-unknown-linux-gnu"]
    x86_bare["x86_64-unknown-none"]
    riscv64["riscv64gc-unknown-none-elf"]
    aarch64["aarch64-unknown-none-softfloat"]
end
subgraph Dependencies["Dependencies"]
    tock_registers_dep["tock-registers = 0.8"]
    no_std["#![no_std]"]
    const_features["const_option, const_nonnull_new"]
end
subgraph subGraph1["Core Implementation"]
    pl011_mod["src/pl011.rs"]
    Pl011Uart_struct["Pl011Uart struct"]
    Pl011UartRegs["Pl011UartRegs struct"]
    methods["UART methods"]
end
subgraph subGraph0["Public API"]
    lib_rs["src/lib.rs"]
    Pl011Uart_export["pub use Pl011Uart"]
end

Pl011Uart_struct --> Pl011UartRegs
Pl011Uart_struct --> methods
lib_rs --> Pl011Uart_export
lib_rs --> aarch64
lib_rs --> const_features
lib_rs --> linux_gnu
lib_rs --> no_std
lib_rs --> pl011_mod
lib_rs --> riscv64
lib_rs --> x86_bare
pl011_mod --> Pl011Uart_struct
pl011_mod --> tock_registers_dep

Sources: src/lib.rs(L1 - L8) Cargo.toml(L14 - L15)

Key Features

The arm_pl011 crate provides the following core capabilities:

Feature	Description	Code Entity
Type-safe register access	Memory-mapped register operations with compile-time safety	tock-registersintegration
UART initialization	Hardware setup and configuration	Pl011Uart::init()
Character I/O	Blocking send/receive operations	putchar(),getchar()
Interrupt management	Interrupt status checking and acknowledgment	is_receive_interrupt(),ack_interrupts()
Multi-target support	Cross-compilation for embedded and hosted environments	no_stdcompatibility
Const operations	Compile-time initialization support	const_option,const_nonnull_new

Sources: Cargo.toml(L1 - L12) src/lib.rs(L2 - L3)

Target Use Cases

The crate is designed for several specific embedded development scenarios:

Operating System Kernels: Provides console and debug output for kernel development, particularly within the ArceOS ecosystem
Bootloaders: Early-stage system initialization requiring minimal dependencies and no_std compatibility
Embedded Applications: Direct hardware control in bare-metal ARM systems with PL011 UART controllers
Cross-platform Development: Testing and development on hosted systems before deployment to embedded targets

The multi-target build support enables development workflows that span from Linux-based development environments to bare-metal embedded deployment, making it suitable for both prototyping and production use.

Sources: Cargo.toml(L8 - L12) README.md(L1 - L9)

ArceOS Crates Book

Overview

System Context

Crate Structure and Code Entities

Key Features

Target Use Cases